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Section 4 - Reshanau Lake <br /> TABLE 4-1 <br /> 1995 RESHANAU LAKE MONITORING RESULTS <br /> Total Secchi Total <br /> Phosphorus Chlorophyll-a Transparency Suspended Solids <br /> + Date (µg/1) (µg/1) (meters) (mg/1) <br /> 05/15/95 70 47 1.2 1 <br /> i 06/09/94 70 11 1.5 7 <br /> 07/07/94 100 48 0.6 18 <br /> 07/29/94 110 105 0.35 11 <br /> 08/17/94 140 121 0.3 16 <br /> 09/02/94 140 41 0.65 7 <br /> 09/16/94 130 58 0.5 9 <br /> 10/04/94 70 17 1.25 11 <br /> Average 110 56 0.8 10 <br /> Standard Deviation 31 39 0.4 5 <br /> i - <br /> Total Phosphorus <br /> Total phosphorus (TP) is an important nutrient in lake ecosystems since the algae productivity in <br /> most lakes is limited by the availability of phosphorus. During the 1995 growing season, surficial <br /> TP concentrations in Reshanau Lake ranged from 70 to 140 µg/l and averaged 110 µg/l (Figure <br /> ' 4-2). The peak TP concentrations do not occur until mid summer, after the annual die off of the <br /> dominant macrophyte species Potomogeton crispus (curly-leaved pondweed). For lakes in the <br /> Central Hardwoods Region, an average of 110 µg/l places Reshanau Lake in the worst 25% <br /> (MPCA 1990). <br /> LSecchi Disk Transparency <br /> Secchi disk transparency (SDT) is a measure of water clarity. During 1995, SDT in Reshanau <br /> Lake ranged from 0.3 to 1.5 meters and averaged 0.8 meters. An average SDT of 0.8 meters <br /> places Reshanau Lake in the worst 25% of lakes in the Central Hardwoods Region(MPCA 1990). <br /> A seasonal pattern was evident for SDT(Figure 4-3). The greatest transparency occurred in spring <br /> and the lowest in mid-summer. This pattern mirrored the observed chlorophyll-a concentrations <br /> and the observed total suspended solids concentrations (Figure 4-4). <br /> `I <br /> MONTGOMERY WATSON Page 42 <br />�r <br />